The present invention relates to a shutter driving mechanism for photographic cameras, and more particularly to a shutter driving mechanism having a shutter operating ring rotatable about the optical axis of an objective lens of the camera, whose rotational movement causes an axial movement of the objective lens in order to position the latter in a proper focus position.
Recent photographic compact cameras are usually equipped with automatic focusing devices. As is well known in the art, the automatic focusing device is a control system for automatically positioning the axially movable objective lens in a desired focus position in order to properly focus an image of a remote subject on the image plane of the camera in response to a signal representative of the distance to the remote subject. These automatic focusing devices comprise an optical focus detecting means and a lens positioning means which includes a member movable in response to the focus detecting operation. Therefore, such cameras include driving mechanisms for the movable member incorporated therein.
On the other hand, a recent tendency in compact cameras is to provide a shutter operating ring, which is rotated about the optical axis of an objective lens by means of a motor or electromagnetic coil to open and close shutter blades. In accordance with such a shutter driving device, a mechanism can be arranged around the objective lens and operationally linked with the shutter blade. This arrangement is beneficial to make cameras thin. Furthermore, since the opening and closing of the shutter blades are driven by an electromagnetic force, exposure controls can be advantageously performed with a high accuracy.
The above-described movable member is generally formed as a focusing ring which is mounted around the objective lens for rotatable movement. For this reason, if it is desired to arrange the shutter operating ring rotatable around the axis of the objective lens for opening and closing the shutter blades, driving mechanisms both of the focusing ring and of the shutter operating ring are concentrated around the objective lens, resulting not only in a complicated structure but also in a troublesome assembling operation.
Therefore, the present invention has as its object to provide a shutter driving mechanism which allows to arrange a shutter driving ring and a focusing ring around the objective lens.
It is another object of the present invention to provide a shutter driving mechanism in which a shutter operating ring can cause, as a result of its rotational movement, a focusing ring to rotate around the axis of the objective lens so as to produce axial movement of the objective lens.
It is still another object of the present invention to provide a shutter driving mechanism which makes it unnecessary to provide any driving mechanism separately for a focusing ring.
It is a further object of the present invention to provide a shutter driving mechanism which can avoid a complicated structure and troublesome assembly operations.